fix: use accent-dark with nord5 light override for prayer backgrounds

var(--color-bg-secondary) from app.css is not available since app.css
is never imported. Use var(--accent-dark) from nordtheme.css with
explicit light mode overrides using var(--nord5).

src/routes/[faithLang=faithLang]/[prayers=prayersLang]/Gebet.svelte

@@ -31,7 +31,7 @@ div.gebet{
 }
 .gebet_wrapper{
 	padding: 1em;
-	background-color: var(--color-bg-secondary);
+	background-color: var(--accent-dark);
 	box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
 	max-width: 600px;
 }
@@ -51,6 +51,11 @@ a.gebet-link {
 	color: inherit;
 	display: block;
 }
+@media (prefers-color-scheme: light) {
+	.gebet_wrapper {
+		background-color: var(--nord5);
+	}
+}
 </style>
 
 {#if href}